A Modular Supersonic Ping Pong Gun
A vacuum-powered device that shoots ping pong balls at high subsonic speeds has been used for physics demonstrations for more than a decade. It uses physics that are easily understood by students, even though its operation is not immediately intuitive. The addition of a pressure plenum and nozzle results in muzzle velocities exceeding Mach 1.5. Balls are readily fired through ping pong paddles and sheets of plywood up to 12.7mm (1/2 inch) thick. Popular reaction to the device indicates that it is an effective way to spark interest in physics and engineering.
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